The United Nations Food and Agriculture Organisation (FAO), in a statement on August 29 2011, urged heightened preparedness and surveillance amid signs that a mutant strain of the deadly bird flu virus is spreading in Asia and beyond, the UN News Centre said

While the H5N1 Highly Pathogenic Avian Influenza virus was eliminated from most of the 63 countries infected at its peak in 2006, it remained endemic in six nations. Outbreaks have risen since then, with almost 800 cases recorded between 2010 and 2011, FAO said.

The agency’s chief veterinary officer, Juan Lubroth, said that migrations have helped the virus travel over long distances and expand geographically. In the past two years, the H5N1 virus has shown up in poultry or wild birds in countries that had been virus-free for several years.

Areas recently affected by the virus are found in Israel and the Palestinian territories, Bulgaria, Romania, Nepal and Mongolia.

Lubroth said another cause for concern is the appearance in China and Viet Nam of a variant virus that is able to bypass the defences provided by existing vaccines.

Most of the northern and central parts of Viet Nam, where H5N1 is endemic, have been invaded by the new virus strain, known as H5N1 – 2.3.2.1. The country had suspended its springtime poultry vaccination campaign this year.

Viet Nam’s veterinary services are on high alert and reportedly considering a targeted vaccination campaign this fall. FAO noted that virus circulation in Viet Nam poses a direct threat to Cambodia, Thailand and Malaysia as well as endangering the Korean peninsula and Japan. Wild bird migration can also spread the virus to other continents.

Bangladesh, China, Egypt, India, Indonesia and Viet Nam, where the virus is still firmly entrenched, are likely to face the biggest problems but all countries need to be vigilant, Lubroth said.

"Preparedness and surveillance remain essential," he said. "This is no time for complacency. No one can let their guard down with H5N1."

peaking to UN Radio, Mr. Lubroth said that there is no indication that the new virus strain will behave differently than the previous one or that it is more dangerous to humans. He also noted that all countries, and not just those where the virus is entrenched, should be concerned that it has not been possible to eliminate and contain the H5N1 virus.

Poultry production and marketing will determine how the disease will spread, he pointed out. "Production practices and marketing practices should be better regulated and more hygienic, as the consumer needs to be protected as well as the production facilities because so many people’s livelihoods depend upon poultry and poultry rearing," he said, as quoted by the UN News Centre.

Since 2003 the H5N1 virus has killed or forced the culling of more than 400 million domestic poultry and caused an estimated $20 billion of economic damage across the globe before it was eliminated from most of the 63 infected countries.

It has infected 565 people since it first appeared, killing 331 of them, according to the UN World Health Organization. The latest death occurred earlier in August 2011 in Cambodia, which has registered eight cases of human infection this year – all of them fatal.